The interaction between the spin magnetic moment of an unpaired electron and the nuclear
spin magnetic moments resulting in the splitting of the α (spin up) and β (spin down)
energy levels in an external magnetic field and, thus, in the multiplet pattern of
spectra of radical-like species and transition metal compounds. Two main contributions
to the hyperfine coupling
are usually considered, Fermi
contact and dipolar interactions. The contact interaction is isotropic
and related to the unpaired spin density
at the nucleus
The dipolar interaction is anisotropic, and related to
is the distance between the atom holding the unpaired electron and the nucleus
with non-zero spin.
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook